Attorney General Mark R. Herring of Virginia told the state’s public colleges and universities on Tuesday that children brought to the United States illegally and raised here, the so-called Dreamers, qualified for in-state tuition.

Mr. Herring, a Democrat, issued the legal opinion after Republicans in the General Assembly killed a state Dream Act early this year. It was the second time he acted independently on a controversial policy in his short tenure: In January, days after being sworn in, he refused to defend Virginia against lawsuits challenging its ban on same-sex marriage, a choice that enraged Republican leaders, with some calling for his resignation.

Virginia politics increasingly resembles the polarization of Washington. Gov. Terry McAuliffe, a Democrat, and the Republican-led House of Delegates are deadlocked and headed toward a possible government shutdown over expanding Medicaid under President Obama’s health care law. In the capital, Richmond, there is talk of Mr. McAuliffe’s resorting to executive action to extend Medicaid to the working poor, echoing the president’s efforts to work around Republican opponents in Congress.

Mr. Herring, who won election last year only after a recount, justified his actions on in-state tuition, as on same-sex marriage, by appealing to progressive principles.

“These ‘Dreamers’ are already Virginians in some very important ways,” he said in a statement on Tuesday. “Instead of punishing and placing limits on these smart, talented, hard-working young people, Virginia should extend them an opportunity for an affordable education.”

The Republican leadership of the House accused Mr. Herring of short-circuiting legislative debate.

“We are deeply concerned by the attorney general’s actions today and what appears to be a continued willingness to ignore and circumvent the duly adopted laws of the Commonwealth,” said a statement by Speaker William J. Howell; the majority leader, Kirk Cox; and other Republican leaders.

In a letter to the presidents of the state’s public colleges and universities, Mr. Herring said young people brought illegally to the United States whose deportations had been deferred under a federal program were entitled to in-state tuition, provided that they met the Virginia residency requirements for all students.

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Mr. Obama set up the program, known as Deferred Action for Childhood Arrivals, in the heat of the presidential campaign in 2012, when immigration policy was politically ablaze. Mitt Romney, the Republican nominee, opposed tuition breaks for the children of illegal immigrants. The president’s initiative allowed some 1.7 million people brought to the country before the age of 16 to apply for de facto residency.

Eighteen states have Dream Acts allowing undocumented students to pay in-state tuition, which is much lower. One immigration law expert, Michael A. Olivas of the University of Houston Law Center, said students who qualified under the federal deferred deportation program, which granted them “legal presence” in the country, could qualify for in-state tuition in all 50 states. Lawsuits are underway in some states, including Arizona and Georgia, to force them to allow qualified immigrants to pay in-state tuition.

A suit filed in Virginia last year by immigrant students who had graduated from state high schools but were struggling to complete college while paying out-of-state tuition was withdrawn on Tuesday.

Mr. Herring’s office said about 8,100 Virginians had been approved under the deferred deportation program. They were required to have no criminal record and to be a high school graduate, enrolled in school or honorably discharged from the military. To qualify for in-state tuition, they must meet the same requirements as other students, including one continuous year of Virginia residency.

Alfonso H. Lopez, a Democrat in the House of Delegates, called the attorney general’s action the right thing to do economically as well as morally. “We invest in these students from kindergarten through 12th grade, but put up a barrier after graduation that only serves to drive away top talent from Virginia,” Mr. Lopez said in a statement.

During debate over a state Dream Act this year, some opponents said it would allow students in the country illegally to take positions from other Virginia residents, including legal immigrants.

A version of this article appears in print on April 30, 2014, on Page A16 of the New York edition with the headline: Virginia Attorney General Opens In-State Tuition to Students Brought to U.S. Illegally. Order Reprints|Today's Paper|Subscribe